#include <iostream>
using namespace std;

struct Base {
    void f() { cout << "B::f "; } // non-virtual
    void g() { cout << "B::g "; } // non-virtual
    virtual void h() { cout << "B::h "; } // virtual
};
struct Derived : public Base {
    void g() { cout << "D::g "; } // replace, non-virtual
    void h() { cout << "D::h "; } // replace, virtual
    void e() { cout << "D::e "; } // extension
};
int rtn( Base &bp ) {		// inheritance polymorphism
    bp.f();			// pointer type (non-virtual)
    bp.g();			// pointer type (non-virtual)
    ((Derived &)bp).g();	// pointer type (coercion!)
    bp.Base::h();		// explicit selection
    bp.h();			// object type (virtual)
}
int main() {
    Base b;
    Derived d;

    Base &b1 = b;
    Base &b2 = *new Base();	// same as b1
    Base &b3 = d;
    Base &b4 = *new Derived();	// same as b3

    rtn( b1 ); cout << endl;
    rtn( b2 ); cout << endl;
    rtn( b3 ); cout << endl;
    rtn( b4 ); cout << endl;
    d.e(); cout << endl;
}